Wireless temperature profiling system

ABSTRACT

A wireless temperature profiling system and the methods of making it are disclosed. The wireless temperature profiling system can include a photovoltaic substrate, a transponder, and a reader.

CLAIM OF PRIORITY

This application claims priority to U.S. Provisional Patent ApplicationNo. 61/145,105, filed on Jan. 15, 2009, which is incorporated byreference in its entirety.

TECHNICAL FIELD

This invention relates to a wireless temperature profiling system andthe methods of making it.

BACKGROUND

Temperature profiling is the process of recording and interpretingtemperatures of products and/or air through a conveyorized process. Byanalyzing the profile, it can be possible to verify products are of thehighest quality, increase throughput, and solve production problems.Accurate temperature profiling gives process engineers reliable data tooptimize the process, improve process control, and make corrections whenrequired.

DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic illustration of a typical temperature profilingsystem.

FIG. 2 is a general block diagram of an embodiment of a transponder.

FIG. 3 is a perspective view of an embodiment of a transponder.

FIG. 4 is a perspective view of the transponder shown in FIG. 3 with anencapsulation.

FIG. 5 is a perspective view of another embodiment of a transponder.

FIG. 6 is a general electrical diagram of an embodiment of atransponder.

FIG. 7 is a perspective view of another embodiment of a transponder.

FIG. 8 is a general electrical diagram of the embodiment of atransponder shown in FIG. 7.

DETAILED DESCRIPTION

To measure the temperature profile during a photovoltaic modulemanufacturing process, a wireless temperature profiling system mayinclude at least one transponder and at least one reader. Thetransponder can be adjacent to a photovoltaic substrate and send atemperature signal corresponding to an environment temperature. Thereader can send sweep signals and pick up the temperature signal fromthe transponder. The transponder can be a passive wireless device.Therefore, no power source is needed for the transponder and thetransponder can be placed separately without power wire or connection toa record device, resulting in higher accuracy and flexibility of thetemperature profile measurement.

In one aspect, a wireless temperature profiling system may include aphotovoltaic substrate, a transponder, and a reader. The transponder canbe adjacent to the photovoltaic substrate and can send a temperaturesignal corresponding to an environment temperature. The reader can sendsweep signals and pick up the temperature signal from the transponder.The reader may include a frame antenna in communication with the readerand receiving the temperature signal from the transponder. The readermay include memory storing data received from the transponder and a dataoutput interface configured to connect the reader with a host system.The reader can be connected to a power source. The transponder can be apassive device. The transponder may include a thermometer. Thethermometer can be a resistance thermometer. The transponder may includea transmitter to send the temperature signal and a piezoelectric energyharvester driving the transmitter.

The transponder may include a radio-frequency poweredinductive-capacitive sensor (known as an “LC sensor”). The transpondermay include a metal spiral inductor as a part of the radio-frequencypowered LC sensor. The transponder may include an inductance temperaturedependent material, an inductance temperature dependent device, acapacitance temperature dependent material, or a capacitance temperaturedependent device. The capacitance temperature dependent device mayinclude a high temperature ceramic material, beryllium oxide, aluminumnitride, alumina, machinable glass-ceramic, or MACOR.

The transponder can be encapsulated. The working frequency of thewireless temperature profiling system can be 30 kHz to 3 GHz, 30 kHz to300 kHz, 3 MHz to 30 MHz, 300 MHz to 3 GHz.

In another aspect, a method of making a transponder reading anenvironment temperature can include providing a photovoltaic substrate,providing a transponder adjacent to the substrate which reads anenvironment temperature and returns a temperature signal correspondingto the temperature, providing a reader which sends a sweep signal andpicks up the temperature signal from the transponder, generating atemperature signal from the transponder, receiving the temperaturesignal with an antenna connected to the reader, and converting thetemperature signal to a corresponding temperature. The method canfurther include providing a thermometer. The method can further includeproviding a resistance thermometer and providing a transmitter connectedto the thermometer. The method can further include providing apiezoelectric energy harvester.

The method can further include providing a radio-frequency powered LCsensor, an inductance temperature dependent material, or a capacitancetemperature dependent material.

In another aspect, a wireless temperature profiling system may include aplurality of transponders and a plurality of readers. The transponderscan be adjacent to a photovoltaic substrate and can move along theinterrogation path. Each of the transponders can simultaneously send atemperature signal corresponding to an environment temperature. Thereaders can be placed along the interrogation path. Each of the readerscan simultaneously send a sweep signal and pick up a signal from atransponder. Each of the readers may include a frame antenna incommunication with the reader, memory storing data received from thetransponder, and a data output interface configured to connect thereader with a host system. The transponder can be a passive device.

Each of the transponders can include a thermometer. Each of thetransponders can include a resistance thermometer. The transponder caninclude a transmitter to send the temperature signal and a piezoelectricenergy harvester driving the transmitter. Each of the transponders mayinclude a radio-frequency powered LC sensor. Each of the transpondersmay include a metal spiral inductor as a part of the radio-frequencypowered LC sensor. The working frequency of the wireless temperatureprofiling system can be 30 kHz to 3 GHz. Each of the transponders mayinclude an inductance temperature dependent material, an inductancetemperature dependent device, a capacitance temperature dependentmaterial, or a capacitance temperature dependent device. The capacitancetemperature dependent device may include a high temperature ceramicmaterial.

Referring to FIG. 1, wireless temperature profiling system 100 mayinclude at least one passive transponder 1, at least one reader 2 tocommunicate with the transponder 1 and manage standard data outputinterface 6. Host system (e.g., computer) 7 interfaces with reader 2 anddirects the interrogation of transponder 1 disposed on or embedded incarrier 4 moving along interrogation path 5 and any following action viaparallel, serial or bus communications 8. Reader 2 can be placed alongan interrogation path 5 to provide an active RF interrogation zone.Carrier 4 can be a conveyer. Carrier 4 can be an article being conveyed,such as a photovoltaic substrate being processed to form a photovoltaicmodule.

Each reader 2 may have frame antenna 3 and standard data outputinterface 6 (e.g., SI8, SI9, or other interfaces of RS232 standard,other single-wire or multi-wire serial binary data interface, interfacesof USB, interfaces of parallel communication, or interfaces of GPIB).The working frequency of the system can be 30 kHz to 3 GHz, for example,30 kHz to 300 kHz, 3 MHz to 30 MHz, and 300 MHz to 3 GHz.

Reader 2 outputs a sweep signal from antenna 3, which picks up atemperature signal from transponder 1, which corresponds to a specifictemperature. A plurality of transponders 1 can be disposed onphotovoltaic modules 200 or embedded in carrier 4 moving alonginterrogation path 5, allowing simultaneous readings to be taken fromeach transponder 1. In this way, a more complete temperature profile canbe obtained than by reading a single transponder at a time.

The temperature signal from transponder 1 can communicate any valuewhich is correlated to a specific temperature. For example, referring toFIG. 2, transponder 70 may include resistance temperature detector (RTD)72, piezoelectric energy harvester 73, and transmitter 71. Transmitter71 may include antenna 74. Resistance temperature detector (RTD) 72detects the environment temperature. Transmitter 71 sends thetemperature signal from resistance temperature detector (RTD) 72.Transmitter 71 and resistance temperature detector (RTD) 72 can bedriven by piezoelectric energy harvester 73.

A passive transponder can be configured to respond to an external sweepsignal by communicating the information that correlates to temperature.For example, referring to FIG. 3, passive transponder 13 may includemetal spiral inductor 14 and temperature dependent capacitor 9.Temperature dependent capacitor 9 may have a first end 10, a second end12, and an insulator layer 11 made of capacitance temperature dependentmaterial. Metal spiral inductor 14 can be electrically connected to thetemperature dependent capacitor 9 with conductive wire 15 at the contactpoint 16. The conductive wire 15 can be attached to the temperaturedependent capacitor 9 by soldering, wire bonding, silver epoxy or otherconductive adhesive. Insulator layer 11 can be made of high temperatureceramic material, beryllium oxide, aluminum nitride, alumina, machinableglass-ceramic, or MACOR.

Referring to FIG. 4, encapsulated passive transponder 18 may includepassive transponder 13 in FIG. 3 and encapsulation 17. The encapsulationcan be done with Low temperature co-fired ceramic (LTCC).

Referring to FIG. 5, passive transponder 19 may include metal spiralinductor 25 and temperature dependent capacitor 20. Temperaturedependent capacitor 20 may have first end 21, second end 23, andinsulator layer 22 made of capacitance temperature dependent material.Metal spiral inductor 25 may include coil 27 of conducting material(e.g. copper wire) wrapped around core 26 of ferromagnetic material.Metal spiral inductor 25 can be electrically connected to temperaturedependent capacitor 20 with conductive wire 24 at contact point 33.Conductive wire 24 can be attached to temperature dependent capacitor 20by soldering, wire bonding, silver epoxy or other conductive adhesive.Insulator layer 22 can be made of high temperature ceramic material,beryllium oxide, aluminum nitride, alumina, machinable glass-ceramic, orMACOR.

Referring to FIG. 6, equivalent circuit of a transponder 28 may includeinductance L_(S) 29, temperature dependent capacitor C_(S) 31, and ohmicresistance in the sensor R_(S) 30. When the value of temperaturedependent capacitor C_(S) 31 changes with environment temperature,impedance Zs 32 of transponder 28 changes too. Therefore, theenvironment temperature can be determined by tracking the resonantfrequency of transponder 28.

Referring to FIG. 7, passive transponder 40 may include metal spiralinductor 45, temperature dependent capacitor 41, and temperaturesensitive diode 48. Temperature dependent capacitor 41 may have firstend 42, second end 44, and insulator layer 43 made of capacitancetemperature dependent material. Metal spiral inductor 45 can beelectrically connected to temperature dependent capacitor 41 andtemperature sensitive diode 48 with conductive wire 46. Conductive wire46 can be attached to temperature dependent capacitor 41 and temperaturesensitive diode 48 by soldering, wire bonding, silver epoxy or otherconductive adhesive. Insulator layer 43 can be made of high temperatureceramic material, beryllium oxide, aluminum nitride, alumina, machinableglass-ceramic, or MACOR.

Referring to FIG. 8 as a general electrical diagram of an embodiment ofa transponder shown in FIG. 6 when the transponder is in its “On”(resonating) state, equivalent circuit of a transponder 50 may includeinductance L_(S) 51, temperature dependent capacitor C_(S) 53, ohmicresistance in the sensor R_(S) 52, inductance L_(d) 54 in temperaturesensitive diode (48 in FIG. 7), temperature dependent capacitor C_(d) 55in temperature sensitive diode (48 in FIG. 7), and ohmic resistanceR_(d) 56 in temperature sensitive diode (48 in FIG. 7). When the valueof temperature dependent capacitor C_(S) 31 and C_(d) 55 changes withenvironment temperature, impedance Zs 57 of transponder 50 changes too.Therefore, the environment temperature can be determined by tracking theresonant frequency of transponder 50. By adding temperature sensitivediode (48 in FIG. 7), the Q value of resonating transponder 50 can befurther controlled to get better performance.

A number of embodiments of the invention have been described.Nevertheless, it will be understood that various modifications may bemade without departing from the spirit and scope of the invention. Itshould also be understood that the appended drawings are not necessarilyto scale, presenting a somewhat simplified representation of variouspreferred features illustrative of the basic principles of theinvention.

What is claimed is:
 1. A system for measuring an environment temperatureof a photovoltaic substrate during a photovoltaic module manufacturingprocess, comprising: a transponder adjacent to the photovoltaicsubstrate which measures the environment temperature during thephotovoltaic module manufacturing process and sends a temperature signalcorresponding to the environment temperature; and a reader which sends asweep signal and picks up the temperature signal from the transponder.2. The wireless temperature profiling system of claim 1, furthercomprising a frame antenna in communication with the reader, wherein theframe antenna receives the temperature signal from the transponder. 3.The wireless temperature profiling system of claim 1, wherein the readercomprises memory storing data received from the transponder.
 4. Thewireless temperature profiling system of claim 1, wherein the readercomprises a data output interface configured to connect the reader witha host system.
 5. The wireless temperature profiling system of claim 1,wherein the reader is connected to a power source.
 6. The wirelesstemperature profiling system of claim 1, wherein the transpondercomprises a passive device, including a temperature sensor.
 7. Thewireless temperature profiling system of claim 6, wherein thetransponder comprises a transmitter to send a temperature signal fromthe temperature sensor.
 8. The wireless temperature profiling system ofclaim 7, wherein the transponder comprises an energy harvester drivingthe transmitter.
 9. The wireless temperature profiling system of claim8, wherein the energy harvester comprises a piezoelectric energyharvester.
 10. The wireless temperature profiling system of claim 1,wherein the transponder comprises a radio-frequency powered LC sensor.11. The wireless temperature profiling system of claim 10, wherein thetransponder comprises a metal spiral inductor as a part of theradio-frequency powered LC sensor.
 12. The wireless temperatureprofiling system of claim 10, wherein the transponder comprises aninductance temperature dependent material.
 13. The wireless temperatureprofiling system of claim 10, wherein the transponder comprises aninductance temperature dependent device as a part of the radio-frequencypowered LC sensor.
 14. The wireless temperature profiling system ofclaim 10, wherein the transponder further comprises a capacitancetemperature dependent material.
 15. The wireless temperature profilingsystem of claim 10, wherein the transponder further comprises acapacitance temperature dependent device as a part of theradio-frequency powered LC sensor.
 16. The wireless temperatureprofiling system of claim 15, wherein the capacitance temperaturedependent device comprises a high temperature ceramic material.
 17. Thewireless temperature profiling system of claim 15, wherein thecapacitance temperature dependent device comprises beryllium oxide,aluminum nitride, alumina, or a machinable glass-ceramic.
 18. Thewireless temperature profiling system of claim 15, wherein themachinable glass-ceramic comprises MACOR.
 19. The wireless temperatureprofiling system of claim 1, wherein the transponder is encapsulated.20. The wireless temperature profiling system of claim 1, wherein theworking frequency of the system is 30 kHz to 3 GHz.
 21. The wirelesstemperature profiling system of claim 1, wherein the working frequencyof the system is 30 kHz to 300 kHz.
 22. The wireless temperatureprofiling system of claim 1, wherein the working frequency of the systemis 3 MHz to 30 MHz.
 23. The wireless temperature profiling system ofclaim 1, wherein the working frequency of the system is 300 MHz to 3GHz.
 24. The wireless temperature profiling system of claim 1, whereinthe transponder is provided on the substrate.
 25. The wirelesstemperature profiling system as in claim 1, wherein the transponder isprovided on a carrier which moves the substrate.
 26. A method of readingan environment temperature of a photovoltaic substrate during aphotovoltaic module manufacturing process, the method, comprising:providing a transponder adjacent to the photovoltaic substrate whichreads an environment temperature during the photovoltaic modulemanufacturing process and returns a temperature signal corresponding tothe temperature; providing a reader which sends a sweep signal and picksup the temperature signal from the transponder; generating a temperaturesignal from the transponder; receiving the temperature signal with anantenna connected to the reader; and converting the temperature signalto a corresponding temperature.
 27. The method of claim 26, wherein thetransponder comprises a temperature sensor which provides thetemperature signal.
 28. The method of claim 27, wherein the transponderfurther comprises a transmitter to send the temperature signal.
 29. Themethod of claim 28, wherein the transponder comprises a piezoelectricenergy harvester, a radio-frequency powered LC sensor, and thetemperature sensor comprises an inductance temperature dependentmaterial, or a capacitance temperature dependent material.
 30. Awireless temperature profiling system for communicating with at leastone transponder moveable along an interrogation path comprising: aphotovoltaic substrate moving along said interrogation path duringprocessing to form a photovoltaic module; a plurality of transpondersadjacent to the photovoltaic substrate moving along the interrogationpath, wherein each of the transponders simultaneously sends atemperature signal corresponding to an environment temperature; aplurality of readers along the interrogation path, wherein each of thereaders simultaneously sends a sweep signal and picks up a signal from atransponder.
 31. The wireless temperature profiling system of claim 30,wherein each reader comprises a frame antenna, memory storing datareceived from a transponder, and a data output interface configured toconnect the reader with a host system.
 32. The wireless temperatureprofiling system of claim 30, wherein at least one of the transponderscomprise a passive device, including a temperature sensor.
 33. Thewireless temperature profiling system of claim 30, wherein eachtransponder comprises a transmitter to send the temperature signal. 34.The wireless temperature profiling system of claim 33, wherein eachtransponder comprises a piezoelectric energy harvester driving thetransmitter.
 35. The wireless temperature profiling system of claim 30,wherein each transponder comprises a radio-frequency powered LC sensor.36. The wireless temperature profiling system of claim 30, wherein eachtransponder comprises a metal spiral inductor as a part of aradio-frequency powered LC sensor.
 37. The wireless temperatureprofiling system of claim 30, wherein the working frequency of thesystem is 30 k to 3 GHz.
 38. The wireless temperature profiling systemof claim 30, wherein each transponder comprises an inductancetemperature dependent material.
 39. The wireless temperature profilingsystem of claim 30, wherein each transponder comprises an inductancetemperature dependent device as a part of a radio-frequency powered LCsensor.
 40. The wireless temperature profiling system of claim 30,wherein each transponder comprises a capacitance temperature dependentmaterial or a high temperature ceramic material.
 41. The wirelesstemperature profiling system of claim 30, wherein each transpondercomprises a capacitance temperature dependent device as a part of aradio-frequency powered LC sensor.
 42. The wireless temperatureprofiling system of claim 30, wherein the transponder is provided on thesubstrate.
 43. The wireless temperature profiling system as in claim 30,wherein the transponder is provided on a carrier which moves thesubstrate.